The multifunctional chair can be unfolded as a reclining chair or a massage chair, and the multifunctional chair can also move up and down as a general office or household seat after being retracted, so that a plurality of use requirements can be brought to people, and therefore, the method is popular among a great number of users. The chair frame of the multifunctional chair generally includes a seat part and a pedal part which can be unfolded or retracted. A motor telescopic rod mechanism and a plurality of connecting rod structures are installed below the chair frame of the seat part to realize unfolding and retracting of the pedal part of the multifunctional chair, and upward and downward movements of the seat.
Referring to the existing chair frame used for manufacturing the multifunctional chair as shown in FIG. 1, the chair frame includes a base 10, wherein the base 10 includes a base front supporting tube 12 and a base rear supporting tube 14, a base right supporting tube 16 and a base left supporting tube 18 (see FIG. 4). The pair of pedal supports 42 is connected to the front driving tube 40 through a connecting rod mechanism, and one end of the main motor telescopic rod mechanism 50 is fixedly connected to the front driving tube 40, and the other end of the main motor telescopic rod mechanism 50 is fixedly connected with the base rear supporting tube 14. The left handrail support 36 and the right handrail support 36 are connected and fixed to the two ends of the backrest front driving tube 34, the front driving tube 34 is connected to the front driving tube 40 through a connecting rod mechanism, and one end of the backrest motor telescopic rod mechanism 60 is fixedly connected to the backrest front driving tube 34, and the other end of the backrest motor telescopic rod mechanism 60 is fixedly connected to the backrest driving tube 32. The front end of the upper frame 20 is fixedly welded to the upper portion of the connecting piece 26, and the front end of the lower frame 30 is connected to the lower portion of the connecting piece 26 through rivets.
As to the multifunctional chair made of the chair frame, the front driving tube 40 which is fixedly connected to the main motor telescopic rod mechanism 50 is driven by the main motor telescopic rod mechanism 50, and then the pedals can be stretched out and unfolded through a connecting rod mechanism between the front driving tube 40 and the pedal supports 42. When the user is sitting on the chair upright, generally there is no big problem. However, in many cases, the user can sit close to one side of the chair, even sometimes, the user can directly sit on one side of the pedal (the position pointed to by two arrows in FIG. 1). In this case, the weight of the user body is transmitted to one side of the front driving tube 40 through the connecting rod mechanism. On one hand, the connecting rod mechanism is always connected in a riveting mode, and when too large force is applied to the connecting rod mechanism, the seat tends to be unstable. The deformation of the connecting rod mechanism can be caused after a long period making the seat more unstable. The front driving tube 40 is fixedly connected to the main motor telescopic rod mechanism 50, and the weight of the heavy body can be directly transmitted to the motor telescopic rod. The deformation and bending of the motor telescopic rod can be caused after a long period, thus hindering the stretching and upward and downward movements of the seat, impacting the use by the user. Furthermore, when the weight of the user is too large, it may cause the telescopic rod of the motor to break, so that the seat loses the corresponding functions. These cause quality defects of the product and even damages to the user.
In addition, on an existing chair frame, referring to an amplifying portion of FIG. 1, the connecting mode between the upper frame 20 and the connecting piece 26 is as follows. Firstly, the upper frame 20 of the square tube structure is primarily fixed between the two connecting plates 2601 of the connecting piece 26 through two rivets 206. Next, the top surface of the upper frame and the top of the connecting plate 2061 are aligned and then welded. The edges of the upper frame adjacent to the connecting piece are wholly welded. This connecting and fixing mode has several problems. First, the upper frame 20 and the connecting piece 26 are pre-fixed by two rivets which are horizontally arranged when the upper frame 20 and the connecting piece 26 are primarily positioned. Due to the fact that all the components which are matched with each other unavoidably have the size tolerances, the top surface of the upper frame 20 and the connecting plate 2601 cannot be completely aligned during welding, which increases the difficulty in welding. It is difficult to ensure that the two connecting plates 2601 can be accurately positioned with the upper frame 20, which easily results in a poor welding quality and being scrapped. Further, in order to ensure the connection strength between the upper frame 20 and the two connecting plates 2601 of the connecting piece 26, and avoid the deformation caused after the seat is used for a long time, in the prior art, an integral welding mode of the adjacent edges is adopted, so that the workload of welding is also increased. Similarly, the rear end of the base right supporting tube 16 and the rear end of the base left supporting tube 18 are connected to the connecting piece 25, which has similar connection issues.
Therefore, in view of the problems existing in the prior art, the multifunctional seat frame needs to be improved to improve the stability and the load bearing strength of the seat and reduce difficulty in machining.